MXA roster: MXA’s pre-race pit
board is very complicated.
TEST-RIDER ROULETTE Dear MXA, During my summer vacation, I came to SoCal and got a chance to go to Glen Helen to watch a local race. I was amazed to see the MXA wrecking crew in the pits. They had a line of 10 new bikes, and the test riders seemed to go to the starting line on different bikes in every moto. How does MXA organize its testing at the races? It may look confusing, but each MXA test rider is assigned a bike. He doesn’t get to choose the bike he rides, but is told what to ride based on the information needed. Some test riders will race two different bikes back-to-back for comparison purposes, and, just as often, two or three test riders will race the same bike on the same day to accelerate the learning curve. It looks like a whirlwind of activity, but it is actually all charted out on a pit board before the day starts.
Numbers: A bike’s head angle is
fixed to the frame, not the clamps.
UNDERSTANDING HEAD ANGLES Dear MXA, How does the head angle affect the performance of a bike? I get the impression that the steeper the better, but I base this on all the positive comments about Suzuki handling. Steeper is not always better. Steeper does make a bike turn quicker; however, motorcycles also need to be stable at high speed, so it is necessary to slow the steering down by raking the head angle forward. The degree that the steering axis is raked forward is called the “head angle.” A chassis with a slacker head angle steers less when you turn the handlebars and wants to remain in a straight line (think chopper). A steeper head angle turns quicker and is less stable at speed (think trials bike). How do you measure head angle? You measure the head angle from an imaginary line perpendicular to the ground to where it intersects the angle of the steering axis. The numbers are based on a 90-degree right angle. Motocross bikes typically have head angles in the range of 27. 5 to 26.0 degrees (a 26 degree angle is steeper than a 27. 5 degree angle). Motocross bikes of the ’70s typically had 30-degree head angles. These were called “slack” head angles. Slack is the converse of steep.